Both pneumatic and hydraulic cylinders are manufactured with or without cushions to eliminate destructive hard stops and pounding caused by the tool or the cylinder bottoming out against the cylinder head or cap while traveling at full velocity. Heretofore proximity switches have been employed to provide a visible or other control indication of the otherwise non-visible bottoming out of the corresponding piston at opposite ends of the cylinder.
The cylinders, particularly the pneumatic, without cushions may bang at either end of their stroke. To prevent this banging, the cushion may be installed internally at either or both ends of the cylinder. To visibly indicate when a piston bottoms out within a cylinder at either end of its stroke probes are installed within the corresponding cap and head which senses when the piston "bottoms out" and provides an electrical signal which may be used to light an indicator lamp or to move a valve.
Since the moving piston assembly possesses high kinetic energy because of high mass or velocity, it will bang on bottoming out. Heretofore, adjustable cushions could not be used on clamp cylinders with proximity switches because with ports in all faces of the cap and head there was no room to install a cushion adjusting bleed screw and ball check.